Jackson Jennie A, Mathiassen Svend Erik, Dempsey Patrick G
Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
J Electromyogr Kinesiol. 2009 Jun;19(3):416-27. doi: 10.1016/j.jelekin.2007.11.004. Epub 2007 Dec 21.
To quantify the variance introduced to trapezius electromyography (EMG) through normalization by sub-maximal reference voluntary exertions (RVE), and to investigate the effect of increased normalization efforts as compared to other changes in data collection strategy on the precision of occupational EMG estimates.
Women performed four RVE contractions followed by 30 min of light, cyclic assembly work on each of two days. Work cycle EMG was normalized to each of the RVE trials and seven exposure parameters calculated. The proportions of exposure variance attributable to subject, day within subject, and cycle and normalization trial within day were determined. Using this data, the effect on the precision of the exposure mean of altering the number of subjects, days, cycles and RVEs during data collection was simulated.
For all exposure parameters a unique component of variance due to normalization was present, yet small: less than 4.4% of the total variance. The resource allocation simulations indicated that marginal improvements in the precision of a group exposure mean would occur above three RVE repeats for EMG collected on one day, or beyond two RVEs for EMG collected on two or more days.
通过次最大自主用力（RVE）归一化来量化引入斜方肌肌电图（EMG）的方差，并研究与数据收集策略的其他变化相比，增加归一化努力对职业EMG估计精度的影响。
女性进行四次RVE收缩，随后在两天中的每一天进行30分钟的轻度循环装配工作。工作周期EMG针对每次RVE试验进行归一化，并计算七个暴露参数。确定了归因于受试者、受试者内的天数以及日内周期和归一化试验的暴露方差比例。利用这些数据，模拟了在数据收集期间改变受试者数量、天数、周期和RVE对暴露均值精度的影响。
对于所有暴露参数，均存在因归一化导致的独特方差成分，但较小：占总方差的比例不到4.4%。资源分配模拟表明，对于一天收集的EMG，在三次以上RVE重复时，或对于两天或更多天收集的EMG，在两次以上RVE时，组暴露均值的精度会有边际改善。
